Tracking macular sensitivity and inner retinal thickness in long‐term type 1 diabetes: A five year prospective examination in patients without diabetic retinopathy

Aims/Purpose: To compare macular sensitivity and retinal thickness in patients with long‐term type 1 diabetes mellitus (DM1) without signs of diabetic retinopathy (DR) after 5 years of follow‐up.

Methods: Thirty‐two eyes from 32 long‐term DM1 patients without signs of DR were included. All participants underwent a complete ophthalmological examination, including microperimetry to assess macular sensitivity and spectral domain optical coherence tomography (SD‐OCT) to measure retinal layer thicknesses focusing on inner retinal layers (IRL). The data were compared with results from 5 years prior using parametric tests (paired samples t‐test).

Results: The mean age of the DM1 patients was 43.19 ± 10.17 years, with a mean disease duration of 29.84 ± 8.98 years and good glycaemic control (HbA1c: 7.55 ± 0.90%). Regarding sex distribution, 14 eyes were from female subjects (43.75%) and 18 were from male subjects (56.25%). In 2023, patients exhibited significantly worse best‐corrected visual acuity (BCVA) compared to 2018 (p < 0.001). DM1 patients did not show changes in macular sensitivity in any analysed macular rings over the 5‐year of follow up period. Central macular sensitivity remained unchanged, with a mean of 27.56 ± 2.50 dB in 2018 compared to 27.50 ± 2.49 dB in 2023. Macular integrity showed significant differences between the two time points (p = 0.045). Retinal thickness showed significant differences, particularly in the IRL across most of the Early Treatment Diabetic Retinopathy Study (ETDRS) areas.

Conclusions: Long‐term DM1 patients without DR lesions showed no changes in macular sensitivity after 5 years of follow‐up. However, these patients demonstrated worsened macular integrity and lower BCVA. Additionally, after 5 years, long‐term DM1 patients without DR displayed significant alterations in retinal thickness, especially in the IRL. Longer follow‐up periods should be considered for the evaluation of retinal neurodegeneration.